The Immune System
A cat’s health depends on an efficient immune system that defends its body from disease.
The immune system can be activated by either physical or psychological triggers and under normal conditions should turn on and off as necessary. If the system does not turn on properly, a cat is "immunosuppressed”.
Feline viruses, such as feline immune deficiency virus (FIV); and feline leukemia virus (TeLV), are linked with immune suppression.
The immune system may also turn on at the wrong time or fail to turn off, leading to allergy, asthma, or autoimmune diseases, in which the immune system attacks a vital part of the body.